I feel the same way.... just when I think I got something it turns out to be way more involved and everything starts to sound like a different language...
As always, outstanding. All else aside, I am so glad that you found some competent medical help. The fact that you were misdiagnosed time and again before someone wised up disturbs me as much as your illness. Listen to the doctors, and stay on your feet as much as possible, and we will have JIM W6LG around for a long , long time. Feel better real soon..Best wishes, Julia K5xxx, Texas
Thanks Julia. I have more subjects planned. Some, I hope, will be interesting. Some of them have a different outcome than expected. For me, the videos have been very good therapy. Especially during some difficult times in recent weeks. I am doing some more tests tomorrow. I have new doctors and that has been good. The list of things that were missed is serious and is long. Thanks Julia for watching. 73, Jim
Hey Jim, I am sure whatever subjects you post will be interesting and informative. Relax. I am appalled that the medical people seem to have "missed" some important signs and symptoms. There is no excuse in this modern age. When I was growing in the '50's and 60's, our people were supposed to be much further ahead due to the promise of advances in science and technology. Something happened. I wish for a healthy and happy future for you.
It's also a good means to demonstrating the importance of having multi-band dipole ends (where ribbon wire is used) enough separated to avoid any spark between the dipole wires ends. And where to separate, seems to me almost half length should be separated.
This was incredibly informative. I have trouble wrapping my head around the current/voltage at different points along a dipole. The visualizations here were great. I’ll be coming back to this video in the future.
Thank you very much. I watch those videos and think about how I could have made it better. So, I might redo a few of them. Right now I am still in the process of moving in order to be closer to medical care and relatvies. The TH-cam room/radio room is not yet built. One video is in process and that one is about dipoles. It may actually be a pretty interesting video in that I have a new device that provides graphs of the SWR, impedance and reactance in a way that is not overly technical and is easy to follow. Thanks again for the kind and supportive message. 73, Jim W6LG
Hi Jim, I'm glad that you are posting again after your troubles with the weather. This comes at a time where I'm trying to get a dipole up for 20 and 40 after a long hiatus from Amateur radio. This was very helpful. If you remember, I'm hooked on SDR and coming along quite nicely. WA0RSD - 73's
Cool video! Reminds when I was a kid and my IBEW union member Dad would help us build Halicrafters SW radios for DXing, and we'd get QSL cards from around the world. He'd tell us about the electronics and how to build a great antenna--just like you did! He was big on grounding of course. We even built an AM broadcast station. Anyway, that was over 50 years ago. Thanks for helping me remember that! Love your videos.
Jim, your videos are treasures to the ham community. With the popularity of amateur radio, the lack of "elmer's" is a problem. Your videos in my opinion are cogent, informative and are similar to taking a class. We all could use a - Ham Radio University. W6LG is a place to begin. Your videos get to the point, without excessive time wasting. Ham Nation is more like a show, for entertaining; all well but for most of us swimming in a vast sea of videos, we need a beacon like yours to get to the point. If I were you I may consider changing the name of the video, keeping it simple. This video is more about Dipole antenna's than the tuner, to me the tuner is a part of explanation not separate from the dipole antenna explanation. I know staying on point will yield more viewers and subscribers. Best of luck. W6ADF
The last time I was at a ham club and asked a member to "elmer" me, I was guided to the Internet. There are not a whole lot of people eager to see how you are doing either.
I love the way you teach!!! I can see the many years of experience you have. Being born in 1960 I can relate to a lot of the equipment in your shack. I let my Ham license expire in the early 2000's. I had an advance class license. Last week I passed the tech test. I am back, KC1MCE... I will get the general in January 2020. I am on fire for D-Star
Chris Custer congrats! That’s so awesome! I’m a newbie, 23 years old and just got my first handheld. Will be taking my technicians license test on November 17th. 🤞
Great video! As I never tire of telling my Uni students (and hams): "Just because you have a "good" VSWR does NOT mean your antenna is radiating power efficiently" But I'm sure many just don't believe me. My other favorite, is the blank looks I get when I tell them that the "output impedance" of their transmitter is NOT 50 ohms! At least the students who have just studied Thevenin's Theorem can understand that one!
Great video Jim i remember my first dipole i wasn't even a ham back then i cut it for 11 meters used a chassis mount just as you did and worked a guy in Texas from my house in Ohio on 4 watts with an old mobile. Needless to say i was hooked thanks again that brought back some fond memories .
I can remember using the same formula to determine antenna length years ago. I probably learned about it in one of the old electronics magazines back in the early 90's when I received my Electronics Technician certificate. As I recall, the formula accounts for stray capacitances, and is easy to remember!
Back in my novice days, in '78, I acquired a 300 watt 50 Ohm resistor. I saw the ads you were talking about and put the resistor between the elements of an Inverted V cut for the novice band on 80 meters. When tuning the receiver, you could tell when the antenna was out of resonance. It had a little noticeable loss on 80 meters where the antenna was cut for, but it worked rather well. On harmonics, it seemed to work ok, as well. But, when it was out of resonance, you could hear the signal strength of radio stations fade. | Basically, the answer I got from the experts in the field were pretty consistent. When an antenna was in resonance, the resistor burned up less power than when the antenna was non-resonant. In an emergency situation, you could actually use it in a 20 meter dipole and communicate on 75 meters, but you would definitely not compete with the standard loaded dipole for the same frequency and power levels. On bands like 20 meters, where it was resonant, when conditions are good, you might not be able to notice the difference since so many signals were overwhelmingly good. But, it will radiate. As for your light bulb dummy load, I can't compare your exact antenna with the light bulbs, but we did have a fellow check into the GA SSB Net at night on a light bulb dummy load occasionally just because he could. So, don't be in a hurry to get rid of those lights.
Hi, Jim. I think I've worked you sometime in the past, but I can't be sure since I left the ham scene some 20 years ago and all my records are now gone. Trying to get my son-in-law interested and I might give it another go if I don't drop off the planet first. Like your approach to these video sessions. Clear, concise, informative, and no Bravo Sierra. J. N6ZJV (gen). 73
Great video and very informative. I am not a HAM but have been studying antennas recently, especially dipoles, in an attempt to improve FM reception in a rural area,. I'n recent weeks ve built several dipoles tuned for my FM stereo, scanner and weather radios and wish I had discovered their performance benefit sooner. I always thought they were inferior, probably because of the flat lead that suppliers used to wad up and include with radios, but that changed once I began making my own.
I too have been trying for years to make the perfect antenna for rural reception but different stations seem to need separate antennas. I would like to know what you came up with.
@@OhmSteader I went simple. I used a calculator to determine the exact length for 93.7Mhz because I wanted to use a very small transmitter on my property in the country, and that was the cleanest freq. available. I used it for a while but it worked a little too well. The TX greatly extended beyond my property so I left it about 15 feet in the air and used it for RX only. I was able to pull in stations I had never heard before, but unfortunately, they all use the same or similar programming services and hearing more of the same was a little disappointing. It's still works but I almost never use it. My other dipoles were made the same way and still work well for their intended purpose, especially the one on my weather radio. I used Beldon RG-6 tri-shield with minimal roll off in the FM band and placed the antenna inside PVC pipe. I used zip ties with eyelets and end caps keep the #12 copper wire tight.
Hi Jim. I have watched a few of your videos and I am enjoying them very much. I recently watched one from a year ago, and am so glad to read you are well and have recovered from your pulmonary embolism a year ago. I am totally new to HAM, and will be sitting my foundation exam here in theUK in a few weeks. I wanted to let you know I will be watching many more of your excellent videos. Thank you very much for what you do. Greetings from South Wales, in the UK.
Thanks Jim. The mysteries of antennas. One works and then we develop theories why it works. Other tests reaffirm those or refute those theories. Like building a bridge. You build it like other bridges that stay up and develop theories as to why it stays up. If it fails under a specific load, more theories, and back to the drawing board. You have a really nice presentation manner. Hugh Jones VE7YJ
Jim, This is my 1st time writing to you. I think I have watched all of your videos now, starting back in September. Your videos have helped me tremendously! Since mid Sept, I've gone to not being involved in ham radio, to 5 weeks later passing my Extra test. I've read with great interest your medical journey (horrifying!), to your near disaster with the fire. I wish you all the best! and I sincerely hope you keep making videos, they help me a LOT! By the way, I heard you on the air, not all that long ago. That put a smile on my face! Additionally, I added a comment down below in this comment section, that is a reply, to a reply, to another commenter not understanding how the voltage and current change along the length of a dipole. I try to explain the way I visualize it, in the hope that it helps. Please check me for accuracy. Many thanks! Dave - KD9JKG
Hello Jim ! I enjoyed your video very much. I like your style of "teaching" --- slow, clear and methodical :) I have subbed and look forward to future video topics. Matter of fact, I plan to go backwards, and doing a search for your past videos as well ! Happy Holidays from N4BRM in SW Florida
Hi JIm: I lived in Tuolumne in the 70's. I listen to you and I think we contacted one another in the last two years. I now live in TN KA1KIX Great videos.
Just discovered your wonderful channel, Jim, and it looks like my weekend will be spent watching. I especially loved the "instantaneous antenna tuner." Keep up the great work. --Mark, KE6BB
My first 2 meter antenna was made very similar to that. I used coat hanger wire soldered to an SO-239. The wire soldered to the center pin was vertical, and I soldered four radials bent at a 45 ish degree downward to the four corners of the SO-239. Hung from the ceiling inside my "shack", it worked all the local repeaters just fine. Better than the "duck" antenna that came with whatever handheld I had at the time.
I alway learn something from you Jim. And you are pleasant to listen to. I just pasted my tech exam. Back in 1975 I got my 2nd Class Ticket. We were big into CB’s then.
Another great video, Jim! I love how you show off the dummy load antenna! That Christmas light dipole is going to look very festive up on Wolf Mountain this winter. :)
Hi Jim I'm N6DBH Var in Fresno. enjoyed your show as I always said a hi dipole is better thn a lo beam, The feedpoiny location is paramount. The Hi current location should be at th highrst point possible, but also the hi volyage points should be away from ground to stop or weaken the leakage by capacitance toground. 73's from N6DBH a friend of Joe OD5ET who regularly contacts you on 20 when the band isopen.
To light those light I'm guessing thats being fed by a 100 watt transmitter? That makes so much sense that the current is what makes the signal as voltage is just a measure of potential and doesn't do any work: the amps are what do the work turning amps into light/heat in a bulb; torque in a motor; or EM waves in an antenna. Thanks for that I wouldn't have thought of it on my own I figured the antenna was putting out everything evenly.
One of the key things I've learned (so far - I don't know much yet) is that from the electrical perspective, "radiation resistance" and "loss resistance" are identical. Electrical testing can give you clues (loss resistance is mostly flat across frequencies) but you're not testing the efficiency or radiated power of an antenna system until you try it with some kind of receiver or field meter. Similarly, testing a radio-frequency electronic design for functionality can tell you whether the design successfully overcomes its own parasitic resistances. But unless you look for EMI you probably won't notice parasitic antennas hiding among the parasitic resistors. The upside of this equivalence is that dummy loads are a perfectly valid way to test transmitters.
Hello Jim from VE8AP nice video loved it keep them coming please we appreciate your knowledge. I think you will remember are QSO haha QSL I like to say that a lot haha
I really appreciate the comment "wow...for an old guy he seems to know his stuff..." Perhaps some feel only the young have any wisdom with respect to technology. Seems to me I am often going to those experienced operators who are able to open new vistas regarding how things work in the real world as opposed to people that look a few things up on the Internet and style themselves as experts for doing so. I also really appreciate the nit-pickers who point out "your dipole formula is pointless" and questioning his approach based on "velocity factors" as though someone as knowledgeable and experienced as W6LG would not have considered such things. In fact the ARRL has considered it in their formulas. The 234 is only a starting point, as W6LG points out, I think, fairly clearly. Other things affect performance, such as nearby conductive materials (he mentions the wiring on his bench), height of the antenna, etc. I believe such comments say much more about the lack of full understanding on the part of the commenters than it does the knowledge of the presenter in this video. In the end the main purpose of all this is to build an antenna that does not harm the radio but is efficient enough to transmit energy allowing for contacts. Every antenna is a compromise in some way (sacrifice broadbandedness for efficiency on a given frequency versus the opposite, for example). Nice video. I will view more of them.
Another very good video. A caution though about end feeding a half wave wire (discussed near the 9 minute point). The required transformation is 4000 ohms/50 ohms = 80 times or perhaps 5000 ohms/50 ohms = 100 times. These transformations can be accomplished with transformers having a 1:9 to 1:10 turns ratio and this has led to some confusion about using a 9:1 balun. The 9:1 balun performs a 9 times impedance transformation raising the value of a 50 ohm input to 450 ohms of output. The L network tuner is a very good circuit for matching 50 ohm coax to an end fed wire.
Thanks Bill. Can you expand on that a little? In other words, the difference between a 9:1 balun and 1:9 turns ratio. I understand about the L network. I do use them in some of my antennas. Thanks Bill & 73, Jim
Impedance transformation in a transformer results from the square of the turns ratio primary to secondary. Consider an autotransformer consisting of a 27 turn coil tapped 3 turns up from one end (ground). If 50 ohms is across this tap, an impedance transformation of (27/3)^2 =81 times occurs. Then 81 * 50 ohms = 4,050 ohms is presented across the full 27 turn coil giving a good match to the end fed half wave of wire. Mention of L networks in my response was an unintentional red heron! The 9:1 balun does not specify the turns ratio but rather the impedance transformation ratio of the balun. So if the 9:1 balun is used with 50 ohms on the input, the impedance on the output is simply 9 * 50 ohms or 450 ohms, leaving a 10:1 SWR when feeding a 4,000 to 5,000 ohm load.
Excellent Bill. You make a good teacher. Keep in mind that I am not an engineer. Hence, my somewhat silly 1234 formula. A balun is a balanced to unbalanced device that may or may not transform an impedance (1:1). That is, for example, it may be 1:1 or 4:1, 9:1 transformation or some other transformation. That x:1 is not a turns ratio but simply the output to input transformation. The 9:1 balun is not a description of the turns ratio but is a description of the impedance transformation. Is that good so far? For a transformer (a device) used for changing an impedance(s), there may be a stated turns ratio that is used in the description. The square of the turns ratio is the transformation. If that turns ratio is 9:1, then the transformation is the square of that number; 9 squared equals 81. So, it would be 81:1 transformation with a 9:1 turns ratio. I did not mention the 3 turns on the input and the 27 turns on the output to get to the 9:1. Maybe I should have. Thanks Bill. I am trying to think of visual way to show that. Maybe I will resort to another light bulb(s). 73, Jim
Nicely done. I work with our club's training committee and we conduct 4 Tech and 1 General workshops a year. The coincidence of nines in both ratios always generates confusion and some frustration for newcomers. I'm looking forward to your video presentation. No need to go into the 3 turn 27 turn example.
Bill Adams Well explained bill having been out out the hobby 25 years and just getting back in to it used a 73.5 foot end fed wire and a 9.1 unun and so far the ones bought also quite expensive total junk I now understand more from you thank you kindly G0myd
So the dipole characteristics can be shown by this diagram. ZV-------------I-------------VZ It indicates that the impedance and voltage are high on the ends of the dipole, but the current is high at the centre. And you also demonstrate here the best place to put an antenna tuner in your circuit-*between* the feedline and the antenna, not right at the transceiver, in which case the tuner is called an antenna coupler.
Jim: If your Christmas bulbs are in series and the current flows through them it seems that the bulbs near the center should be brightest, not the bulbs on the end since as we know, current is max in the center however you show the opposite. Are these bulbs actually wired up of just picking up RF?
I used a 100-foot long piece of RG-58 with nothing connected to the other end as a dummy load for 70-centimeters. Loss is about 10 db, so by the time the signal makes the round trip back to the transmitter the reflected power is 20db lower than the forward power. You can actually key up repeaters with it too since the coax is so leaky at those frequencies!
This is a very informative video. Just the other day I was wondering if it would be possible to use 50 ohm resistors and then somehow couple the antenna wires to the resistors. 73 KD5YOU
Great video, very thought provoking... Seems a lot of the wire length doesn't actually do very much in terms of radiation.. interesting indeed,, seems to chime with the high efficiency/small size of magloops... maybe I can get on topband after all in my small garden with some wire dipole and capacitive hats... David G0UPK
Another great video Jim. The Christmas lights are cool. But you should not put those up until after Thanksgiving :) While I agree with your comment about end feeding and "typically" using a 9:1, I will add to that that something like a 55:1 UNUN would give a better match. My experience with my end feds show they have up to 4000 ohms of feedpoint impedance and it takes a transformer from 50 to 55:1 ratio to get a match where you dont require a tuner. Consider this an addition and not disagreement.
More than one guy caught my mistake and kindly offered a correction. Thanks. I do appreciate the help. A refresher on the difference between turns ratios and transformation is going to be in a future video. There is always something to learn and that's what makes this fun. Thanks Rich. As I said that number in the video my brain was thinking something is not right! I hope to hear you on 20 meters soon. 73, Jim W6LG
Very interesting, thanks! I would be interested in more antenna videos for sure. After a long break from 11 meters in the 90's, I recently got my General and an FT-991A. Still trying to figure out what kind of antenna I want to get for HF though. 73
Good and welcome. If you can find a local guy to help you, that would be best. View TH-cam videos from most sources as being, well, not the best information. Stick with the videos of a more technical nature. Thanks Robert and good luck. 56 years fo me! Jim Heath
Jim, I thought of an idea for a helpful video. You mentioned in this video you can make a dipole with just about anything and used the Christmas tree light as an example. I would like to see a video on the specifics for loading up random dipoles. Just how to you connect them and then how do you tune them, with what equipment. It seems like I run off into never never land experimenting with such and right now a simple well performing dipole would be great for me. Give it some thought. WA0RSD, 73's
You are correct and great advice for another video. I had not thought about that kind of video. So, I will do it soon. Thanks Doug again for great input. 73, Jim
I really enjoy going back and re-watching these older videos.
BTW, the 1234 trick has worked good for me... Thanks Jim.
This is one of those videos I keep coming back to years later
It took weeks to set that up. Seriously! It is one of my favorite videos. One that I am proud about. Thanks, Jim Heath W6LG
The more videos I watch, the more I feel like the "dummy load." I have soooooo much to learn.
I feel the same way.... just when I think I got something it turns out to be way more involved and everything starts to sound like a different language...
This was excellent ! Taking my tech exam tomorrow and this explanation really helps me to remember the basics about the dipole antenna. Thank you.
Glad it was helpful! 73, Jim
Oldie but goodie. You have the perfect voice for these.
Always informative and refreshing to hear your explanations, Jim. I have been a ham for some 40+ years and still learning something new
THANK YOU!
As always, outstanding. All else aside, I am so glad that you found some competent medical help. The fact that you were misdiagnosed time and again before someone wised up disturbs me as much as your illness. Listen to the doctors, and stay on your feet as much as possible, and we will have JIM W6LG around for a long , long time. Feel better real soon..Best wishes, Julia K5xxx, Texas
Thanks Julia. I have more subjects planned. Some, I hope, will be interesting. Some of them have a different outcome than expected. For me, the videos have been very good therapy. Especially during some difficult times in recent weeks. I am doing some more tests tomorrow. I have new doctors and that has been good. The list of things that were missed is serious and is long. Thanks Julia for watching. 73, Jim
Hey Jim, I am sure whatever subjects you post will be interesting and informative. Relax. I am appalled that the medical people seem to have "missed" some important signs and symptoms. There is no excuse in this modern age. When I was growing in the '50's and 60's, our people were supposed to be much further ahead due to the promise of advances in science and technology. Something happened. I wish for a healthy and happy future for you.
An excellent real-time demonstration of voltage and current distribution. "Where voltage is maximum, current is minimum" defined!
Yes, that physics thing from High School. Thanks Watt for adding that statement. 73, Jim
It's also a good means to demonstrating the importance of having multi-band dipole ends (where ribbon wire is used) enough separated to avoid any spark between the dipole wires ends. And where to separate, seems to me almost half length should be separated.
This was incredibly informative. I have trouble wrapping my head around the current/voltage at different points along a dipole. The visualizations here were great. I’ll be coming back to this video in the future.
Jim, your review of the Mystery Tuner being a dummy load was really good.
So nice to watch a video that makes you feel smarter at the end.
Yes, me too. I do a lot of research before the recording so that I will make fewer mistakes. Thanks Mark. 73, Jim
Fantastic illustrations! You're a natural teacher. Thank you.
Thank you very much. I watch those videos and think about how I could have made it better. So, I might redo a few of them. Right now I am still in the process of moving in order to be closer to medical care and relatvies. The TH-cam room/radio room is not yet built. One video is in process and that one is about dipoles. It may actually be a pretty interesting video in that I have a new device that provides graphs of the SWR, impedance and reactance in a way that is not overly technical and is easy to follow. Thanks again for the kind and supportive message. 73, Jim W6LG
Hi Jim, I'm glad that you are posting again after your troubles with the weather. This comes at a time where I'm trying to get a dipole up for 20 and 40 after a long hiatus from Amateur radio. This was very helpful. If you remember, I'm hooked on SDR and coming along quite nicely.
WA0RSD - 73's
Cool video! Reminds when I was a kid and my IBEW union member Dad would help us build Halicrafters SW radios for DXing, and we'd get QSL cards from around the world. He'd tell us about the electronics and how to build a great antenna--just like you did! He was big on grounding of course. We even built an AM broadcast station. Anyway, that was over 50 years ago. Thanks for helping me remember that! Love your videos.
I'm preparing for my exams and this kind of stuff fills in the stuff that isn't really covered much elsewhere, thanks a bunch!
Jim, your videos are treasures to the ham community. With the popularity of amateur radio, the lack of "elmer's" is a problem. Your videos in my opinion are cogent, informative and are similar to taking a class. We all could use a - Ham Radio University. W6LG is a place to begin. Your videos get to the point, without excessive time wasting. Ham Nation is more like a show, for entertaining; all well but for most of us swimming in a vast sea of videos, we need a beacon like yours to get to the point. If I were you I may consider changing the name of the video, keeping it simple. This video is more about Dipole antenna's than the tuner, to me the tuner is a part of explanation not separate from the dipole antenna explanation. I know staying on point will yield more viewers and subscribers. Best of luck. W6ADF
The last time I was at a ham club and asked a member to "elmer" me, I was guided to the Internet. There are not a whole lot of people eager to see how you are doing either.
Jim. Thanks for this video. I'm new to ham and looking into dipole antennas. Your demonstration helped me understand better how they work.
I love the way you teach!!! I can see the many years of experience you have.
Being born in 1960 I can relate to a lot of the equipment in your shack.
I let my Ham license expire in the early 2000's. I had an advance class license.
Last week I passed the tech test. I am back, KC1MCE... I will get the general in January 2020.
I am on fire for D-Star
Chris Custer congrats! That’s so awesome! I’m a newbie, 23 years old and just got my first handheld. Will be taking my technicians license test on November 17th. 🤞
Another information & interesting video.
The length of these videos (around 15 minutes) is perfect.
Great video! As I never tire of telling my Uni students (and hams): "Just because you have a "good" VSWR does NOT mean your antenna is radiating power efficiently" But I'm sure many just don't believe me. My other favorite, is the blank looks I get when I tell them that the "output impedance" of their transmitter is NOT 50 ohms! At least the students who have just studied Thevenin's Theorem can understand that one!
Great video Jim i remember my first dipole i wasn't even a ham back then i cut it for 11 meters used a chassis mount just as you did and worked a guy in Texas from my house in Ohio on 4 watts with an old mobile. Needless to say i was hooked thanks again that brought back some fond memories .
Sunspots, or the lack of them, makes a huge difference. But there is lots of opportunity to work long distances. Thanks Steve! 73, Jim
You’ve a gift for teaching. Well done.
Insightful. Liked your Christmas dipole as well as your not-so-pretty dipole.
Thanks again Jim for your excellent and informative presentations. I feel I learn something from each one.
I can remember using the same formula to determine antenna length years ago. I probably learned about it in one of the old electronics magazines back in the early 90's when I received my Electronics Technician certificate. As I recall, the formula accounts for stray capacitances, and is easy to remember!
Thanks Dirk. 73, Jim
Jim, thanks, I really need the kind of help that you give. I owe you.
Thanks Bruce. Glad that it helped. If there is another subject that I help in a video, please let me know. 73, Jim W6LG
Back in my novice days, in '78, I acquired a 300 watt 50 Ohm resistor. I saw the ads you were talking about and put the resistor between the elements of an Inverted V cut for the novice band on 80 meters. When tuning the receiver, you could tell when the antenna was out of resonance. It had a little noticeable loss on 80 meters where the antenna was cut for, but it worked rather well. On harmonics, it seemed to work ok, as well. But, when it was out of resonance, you could hear the signal strength of radio stations fade. |
Basically, the answer I got from the experts in the field were pretty consistent. When an antenna was in resonance, the resistor burned up less power than when the antenna was non-resonant.
In an emergency situation, you could actually use it in a 20 meter dipole and communicate on 75 meters, but you would definitely not compete with the standard loaded dipole for the same frequency and power levels. On bands like 20 meters, where it was resonant, when conditions are good, you might not be able to notice the difference since so many signals were overwhelmingly good. But, it will radiate.
As for your light bulb dummy load, I can't compare your exact antenna with the light bulbs, but we did have a fellow check into the GA SSB Net at night on a light bulb dummy load occasionally just because he could. So, don't be in a hurry to get rid of those lights.
Nice video Jim, with an easy to understand explanation of a di-pole, Thanks Jim
Hi, Jim. I think I've worked you sometime in the past, but I can't be sure since I left the ham scene some 20 years ago and all my records are now gone. Trying to get my son-in-law interested and I might give it another go if I don't drop off the planet first. Like your approach to these video sessions. Clear, concise, informative, and no Bravo Sierra. J. N6ZJV (gen). 73
Great video and very informative. I am not a HAM but have been studying antennas recently, especially dipoles, in an attempt to improve FM reception in a rural area,. I'n recent weeks ve built several dipoles tuned for my FM stereo, scanner and weather radios and wish I had discovered their performance benefit sooner. I always thought they were inferior, probably because of the flat lead that suppliers used to wad up and include with radios, but that changed once I began making my own.
I too have been trying for years to make the perfect antenna for rural reception but different stations seem to need separate antennas. I would like to know what you came up with.
@@OhmSteader I went simple. I used a calculator to determine the exact length for 93.7Mhz because I wanted to use a very small transmitter on my property in the country, and that was the cleanest freq. available. I used it for a while but it worked a little too well. The TX greatly extended beyond my property so I left it about 15 feet in the air and used it for RX only. I was able to pull in stations I had never heard before, but unfortunately, they all use the same or similar programming services and hearing more of the same was a little disappointing. It's still works but I almost never use it.
My other dipoles were made the same way and still work well for their intended purpose, especially the one on my weather radio.
I used Beldon RG-6 tri-shield with minimal roll off in the FM band and placed the antenna inside PVC pipe. I used zip ties with eyelets and end caps keep the #12 copper wire tight.
Extremely good video and audio. You are also easy to follow. Thank you. Frank KO4Jup
Hi Jim. I have watched a few of your videos and I am enjoying them very much. I recently watched one from a year ago, and am so glad to read you are well and have recovered from your pulmonary embolism a year ago. I am totally new to HAM, and will be sitting my foundation exam here in theUK in a few weeks. I wanted to let you know I will be watching many more of your excellent videos. Thank you very much for what you do. Greetings from South Wales, in the UK.
Like the low key production. Thank you.
One of the best explanations I’ve ever heard
Thank you!! Wow!! 73, Jim
Thanks Jim. The mysteries of antennas. One works and then we develop theories why it works. Other tests reaffirm those or refute those theories. Like building a bridge. You build it like other bridges that stay up and develop theories as to why it stays up. If it fails under a specific load, more theories, and back to the drawing board. You have a really nice presentation manner. Hugh Jones VE7YJ
Jim w6lg what a interesting hobby to get into is ham radio
Jim, thank you for the informative presentation on dipoles.
Jim,
This is my 1st time writing to you. I think I have watched all of your videos now, starting back in September. Your videos have helped me tremendously! Since mid Sept, I've gone to not being involved in ham radio, to 5 weeks later passing my Extra test. I've read with great interest your medical journey (horrifying!), to your near disaster with the fire. I wish you all the best! and I sincerely hope you keep making videos, they help me a LOT! By the way, I heard you on the air, not all that long ago. That put a smile on my face!
Additionally, I added a comment down below in this comment section, that is a reply, to a reply, to another commenter not understanding how the voltage and current change along the length of a dipole. I try to explain the way I visualize it, in the hope that it helps. Please check me for accuracy.
Many thanks!
Dave - KD9JKG
Great vid! Just passed both the tech and general yesterday. Re-watching your vids. Great content!
Congratulations! 73, Jim
simple way to show the function of dipole antrenna....thanks for share Jim..73..de SV3IRG..
Thanks for taking your time to help others! Nice👍
Hello Jim ! I enjoyed your video very much. I like your style of "teaching" --- slow, clear and methodical :) I have subbed and look forward to future video topics. Matter of fact, I plan to go backwards, and doing a search for your past videos as well !
Happy Holidays from N4BRM in SW Florida
Hi JIm: I lived in Tuolumne in the 70's. I listen to you and I think we contacted one another in the last two years. I now live in TN KA1KIX Great videos.
Just discovered your wonderful channel, Jim, and it looks like my weekend will be spent watching. I especially loved the "instantaneous antenna tuner." Keep up the great work. --Mark, KE6BB
You're looking and sounding well Jim. Thanks for your videos.
My first 2 meter antenna was made very similar to that. I used coat hanger wire soldered to an SO-239. The wire soldered to the center pin was vertical, and I soldered four radials bent at a 45 ish degree downward to the four corners of the SO-239. Hung from the ceiling inside my "shack", it worked all the local repeaters just fine. Better than the "duck" antenna that came with whatever handheld I had at the time.
I alway learn something from you Jim.
And you are pleasant to listen to.
I just pasted my tech exam.
Back in 1975 I got my 2nd Class Ticket.
We were big into CB’s then.
Excellent. Plan on going all the way to the Extra. 73, Jim
So you pasted into the exam the info you copied from here ;)
Finally a good demonstation on how a "dummy load antenna" works! Very good indeed!
Great video. My dipole knowledge is much better now.
Another great video, Jim! I love how you show off the dummy load antenna!
That Christmas light dipole is going to look very festive up on Wolf Mountain this winter. :)
Priceless wisdom, thanks for sharing
Hi Jim I'm N6DBH Var in Fresno. enjoyed your show as I always said a hi dipole is better thn a lo beam, The feedpoiny location is paramount. The Hi current location should be at th highrst point possible, but also the hi volyage points should be away from ground to stop or weaken the leakage by capacitance toground. 73's from N6DBH a friend of Joe OD5ET who regularly contacts you on 20 when the band isopen.
To light those light I'm guessing thats being fed by a 100 watt transmitter? That makes so much sense that the current is what makes the signal as voltage is just a measure of potential and doesn't do any work: the amps are what do the work turning amps into light/heat in a bulb; torque in a motor; or EM waves in an antenna. Thanks for that I wouldn't have thought of it on my own I figured the antenna was putting out everything evenly.
You earned another follower sir
One of the key things I've learned (so far - I don't know much yet) is that from the electrical perspective, "radiation resistance" and "loss resistance" are identical. Electrical testing can give you clues (loss resistance is mostly flat across frequencies) but you're not testing the efficiency or radiated power of an antenna system until you try it with some kind of receiver or field meter.
Similarly, testing a radio-frequency electronic design for functionality can tell you whether the design successfully overcomes its own parasitic resistances. But unless you look for EMI you probably won't notice parasitic antennas hiding among the parasitic resistors. The upside of this equivalence is that dummy loads are a perfectly valid way to test transmitters.
This blew my mind. Learned alot.
"It's gonna get weird in the GHz" EVERYTHING gets weird in the Gigahertz! Lol
thank's jim for your video's i'm fairly new to the hobby hope to catch you on air sometime 73 from Clinton VK6FCRC
Keep making vids W6LG i am new to this looking into a dipole antenna
very good idea illustration to find out high current and high voltage point in the dipole antenna, thank you best theacher...73 de YD1WDL
Mr Jim I’m really enjoying your content, liked and subbed, keep up the great content sir ‘73
KG5AUB
Thanks! 73, Jim
Great info thanks Jim We all love you
Hey Jim! You're looking like you're feeling a lot better lately! Good luck on the 10k subs! 73
Awesome video Jim!
Hi Jim thx for what you doing!!!
Hello Jim from VE8AP nice video loved it keep them coming please we appreciate your knowledge. I think you will remember are QSO haha QSL I like to say that a lot haha
THANKS JIM I LEARN ALOT FROM YOU 73
Thanks! 73, Jim
Thanks for the informative video and keep them coming!
You are very welcome Jeremy. 73, Jim
hi, Jim. Very nice and informative video on basic antenna theory.73 Alan KZ6B
Good show Jim.....
Thank you.
KC3GHC
73.
Thanks ED! 73, Jim
I really appreciate the comment "wow...for an old guy he seems to know his stuff..." Perhaps some feel only the young have any wisdom with respect to technology. Seems to me I am often going to those experienced operators who are able to open new vistas regarding how things work in the real world as opposed to people that look a few things up on the Internet and style themselves as experts for doing so. I also really appreciate the nit-pickers who point out "your dipole formula is pointless" and questioning his approach based on "velocity factors" as though someone as knowledgeable and experienced as W6LG would not have considered such things. In fact the ARRL has considered it in their formulas. The 234 is only a starting point, as W6LG points out, I think, fairly clearly. Other things affect performance, such as nearby conductive materials (he mentions the wiring on his bench), height of the antenna, etc. I believe such comments say much more about the lack of full understanding on the part of the commenters than it does the knowledge of the presenter in this video. In the end the main purpose of all this is to build an antenna that does not harm the radio but is efficient enough to transmit energy allowing for contacts. Every antenna is a compromise in some way (sacrifice broadbandedness for efficiency on a given frequency versus the opposite, for example). Nice video. I will view more of them.
Nice video , Greetings from belgium 73 👍
Another very good video. A caution though about end feeding a half wave wire (discussed near the 9 minute point). The required transformation is 4000 ohms/50 ohms = 80 times or perhaps 5000 ohms/50 ohms = 100 times. These transformations can be accomplished with transformers having a 1:9 to 1:10 turns ratio and this has led to some confusion about using a 9:1 balun. The 9:1 balun performs a 9 times impedance transformation raising the value of a 50 ohm input to 450 ohms of output. The L network tuner is a very good circuit for matching 50 ohm coax to an end fed wire.
Thanks Bill. Can you expand on that a little? In other words, the difference between a 9:1 balun and 1:9 turns ratio. I understand about the L network. I do use them in some of my antennas. Thanks Bill & 73, Jim
Impedance transformation in a transformer results from the square of the turns ratio primary to secondary. Consider an autotransformer consisting of a 27 turn coil tapped 3 turns up from one end (ground). If 50 ohms is across this tap, an impedance transformation of (27/3)^2 =81 times occurs. Then 81 * 50 ohms = 4,050 ohms is presented across the full 27 turn coil giving a good match to the end fed half wave of wire. Mention of L networks in my response was an unintentional red heron!
The 9:1 balun does not specify the turns ratio but rather the impedance transformation ratio of the balun. So if the 9:1 balun is used with 50 ohms on the input, the impedance on the output is simply 9 * 50 ohms or 450 ohms, leaving a 10:1 SWR when feeding a 4,000 to 5,000 ohm load.
Excellent Bill. You make a good teacher. Keep in mind that I am not an engineer. Hence, my somewhat silly 1234 formula.
A balun is a balanced to unbalanced device that may or may not transform an impedance (1:1). That is, for example, it may be 1:1 or 4:1, 9:1 transformation or some other transformation. That x:1 is not a turns ratio but simply the output to input transformation. The 9:1 balun is not a description of the turns ratio but is a description of the impedance transformation.
Is that good so far?
For a transformer (a device) used for changing an impedance(s), there may be a stated turns ratio that is used in the description. The square of the turns ratio is the transformation. If that turns ratio is 9:1, then the transformation is the square of that number; 9 squared equals 81. So, it would be 81:1 transformation with a 9:1 turns ratio.
I did not mention the 3 turns on the input and the 27 turns on the output to get to the 9:1. Maybe I should have.
Thanks Bill. I am trying to think of visual way to show that. Maybe I will resort to another light bulb(s). 73, Jim
Nicely done. I work with our club's training committee and we conduct 4 Tech and 1 General workshops a year. The coincidence of nines in both ratios always generates confusion and some frustration for newcomers. I'm looking forward to your video presentation. No need to go into the 3 turn 27 turn example.
Bill Adams
Well explained bill having been out out the hobby 25 years and just getting back in to it used a 73.5 foot end fed wire and a 9.1 unun and so far the ones bought also quite expensive total junk
I now understand more from you thank you kindly
G0myd
Always good information. Thank you.
So the dipole characteristics can be shown by this diagram.
ZV-------------I-------------VZ
It indicates that the impedance and voltage are high on the ends of the dipole, but the current is high at the centre.
And you also demonstrate here the best place to put an antenna tuner in your circuit-*between* the feedline and the antenna, not right at the transceiver, in which case the tuner is called an antenna coupler.
Great video Jim, hope you are doing well. 73
Thanks! How are you doing? Let's meet on 20 sometime soon. 73, Jim
Wow, one of your great videos has 160K views! Excellent. 73, Jim
Good video, Jim. Thank you.
Jim: If your Christmas bulbs are in series and the current flows through them it seems that the bulbs near the center should be brightest, not the bulbs on the end since as we know, current is max in the center however you show the opposite. Are these bulbs actually wired up of just picking up RF?
This shod take you back few years. '55-'56. KJ6BM. I kind of lost my way after Cambodia, when we not in Cambodia if you get my drift. 73's.
Did you mean K6JBM? KJ6BM would have been on Johnston Island in the 1950's. I did work a few guys from KJ6 land. 73, Jim
I used a 100-foot long piece of RG-58 with nothing connected to the other end as a dummy load for 70-centimeters. Loss is about 10 db, so by the time the signal makes the round trip back to the transmitter the reflected power is 20db lower than the forward power.
You can actually key up repeaters with it too since the coax is so leaky at those frequencies!
Wow! Thanks Ryan. 73, Jim
I discovered this on VHF and UHF repeaters too! Love this stuff! Makes studying for Extra fun.
It is good to learn about this. 73, Jim
Really enjoyed the video!
Thanks Stephen! 73, Jim W6LG
Much enjoyed Jim!
Good video. Good info. Thanks.
This is a very informative video. Just the other day I was wondering if it would be possible to use 50 ohm resistors and then somehow couple the antenna wires to the resistors. 73 KD5YOU
Great video, very thought provoking...
Seems a lot of the wire length doesn't actually do very much in terms of radiation.. interesting indeed,, seems to chime with the high efficiency/small size of magloops... maybe I can get on topband after all in my small garden with some wire dipole and capacitive hats... David G0UPK
Great Video! Thanks Jim!
Another great video Jim. The Christmas lights are cool. But you should not put those up until after Thanksgiving :) While I agree with your comment about end feeding and "typically" using a 9:1, I will add to that that something like a 55:1 UNUN would give a better match. My experience with my end feds show they have up to 4000 ohms of feedpoint impedance and it takes a transformer from 50 to 55:1 ratio to get a match where you dont require a tuner. Consider this an addition and not disagreement.
More than one guy caught my mistake and kindly offered a correction. Thanks. I do appreciate the help. A refresher on the difference between turns ratios and transformation is going to be in a future video. There is always something to learn and that's what makes this fun. Thanks Rich. As I said that number in the video my brain was thinking something is not right! I hope to hear you on 20 meters soon. 73, Jim W6LG
Well I will add that I am not sure a 9:1 is not a bad idea anyway. Guys seem to melt down the 55:1 transformers if they are running any power !
Very interesting, thanks! I would be interested in more antenna videos for sure. After a long break from 11 meters in the 90's, I recently got my General and an FT-991A. Still trying to figure out what kind of antenna I want to get for HF though. 73
Excellent example of the voltage distribution on a dipole.👍☘️EI3KY
Many thanks! 73, Jim
another good video 73s Martin M6LKD
I'm new at this and thinking of getting a Ham license so the more I learn the better.
Good and welcome. If you can find a local guy to help you, that would be best. View TH-cam videos from most sources as being, well, not the best information. Stick with the videos of a more technical nature. Thanks Robert and good luck. 56 years fo me! Jim Heath
I was curious as to how the lights were connected electrically, I am having trouble visualizing a diagram type view of the xmas light dipole.
Jim,
I thought of an idea for a helpful video. You mentioned in this video you can make a dipole with just about anything and used the Christmas tree light as an example. I would like to see a video on the specifics for loading up random dipoles. Just how to you connect them and then how do you tune them, with what equipment. It seems like I run off into never never land experimenting with such and right now a simple well performing dipole would be great for me.
Give it some thought.
WA0RSD, 73's
You are correct and great advice for another video. I had not thought about that kind of video. So, I will do it soon. Thanks Doug again for great input. 73, Jim
Nice video Jim.
Thank you for sharing.
Have fun.
73 de Paul, G4JNN.
Very interesting.
73's Alan in the UK
Welp with 37,000 subscribers you sure beat 10,000.
Jim w6lg I like your utube videos
Hey Jim, Long time no vlog. Hope you are doing better. Keep us posted. Quiet out here. Best, jdm
this is the best explanation ever!
Enjoyed your video and I subscribed. Looking forward to your next one. 73's K9LDO
Thanks Ken! 73, Jim